1. Field of the Invention
The present invention relates to a vehicular pneumatic tire having a tread that is asymmetrically designed relative to a circumference of the running surface, i.e., the tread includes an outside and an inside region, which are related to the vehicle to which the tire is to be mounted, and each region has a shoulder block row. The tread also includes a center region that is laterally delimited by circumferential grooves belonging to the outside or inside region. Further, transverse grooves in the shoulder block row of the inside region are arranged to extend into the center region.
2. Discussion of Background Information
Different embodiments of tires having asymmetrical tread profiles are known from prior art. Asymmetrical tread profiles are fundamentally those that, relative to the vehicle to which the tire will be mounted, have an inside region and an outside region and the profile structures of these regions fundamentally differ from one another. Indeed, with such a profile design it is possible to deliberately influence and optimize specific tire characteristics, e.g., drainage ability, driving behavior, and tire/road noise produced during tire roll.
However, a vehicular pneumatic tire of the type generally described above is simultaneously tied to the direction of rotation and is discussed in, e.g., EP-A 0 718 124. Here, an optimized tread profile with a separate function is proposed in which, in the outside region, a driving surface portion (positive portion) is at least 75% over a width of 30 to 40% of the tread width. In the inside region, between the tread margin and the circumference center line, the driving surface portion is 55 to 65%. In the center region of the tread, a tread strip is arranged to pass through in the circumferential direction. The tread strip runs along a center circumferential line and is structured by blind grooves that run more or less in continuation of all transverse grooves from the shoulder block row of the outside region. The profile structures in the tread center region are each delimited bilaterally by one wide circumferential groove running straight in the circumferential direction. Tires having this known tread profile have good driving characteristics and good water evacuation capabilities, even at higher speeds.
From DE-A1 38 34 383, a vehicular pneumatic tire, which also has a tread profile tied to the direction of rotation, is disclosed which is not designed asymmetrically. To improve drainage ability, i.e., to improve aquaplaning behavior, and to influence or improve noise development, this tread profile is constructed such that it is essentially composed only of a multiplicity of obliquely-oriented rib profile elements running at an acute angle to the tire circumference center line. The profile channels created by these rib profile elements begin in the region of the tire circumference center line and form an angle there of 15 to 30xc2x0 with the center line. In the shoulder regions, the profile channels have kinks, so that the angle of the channels to the tire circumference center line formed there is substantially larger. In the tire shoulder regions, between the already-kinked sections of the profile channels, additional profile channels running parallel thereto are provided. With such a tread profile, drainage capability can be improved, but the rib profile elements running at an acute angle to the tire circumference center line over the majority of the tread width, based on their length, are so narrow that, in tires having such a profile design, uneven wear occurs and, contrary to the assumption expressed in the document, a rather unfavorable noise production would occur.
The present invention provides an asymmetrical tread profile of the type generally described above, which improves drainage ability and favorably influences rolling noise. Moreover, the asymmetrical tread profile of the present invention provides the above advantages while considering the most even possible wear pattern of the tread.
According to the instant invention, the center region of the tread profile can have a width of approximately 25-35% of a tread width, and, e.g., every second transverse groove can be arranged to continue from a shoulder block row of an inside region into the center region as a groove that at least nearly traverses the center region. Grooves in the center region can form an angle with respect to an equator line of a maximum of approximately 30xc2x0 along at least one-third of their longitudinal extension.
Therefore, tread profiles designed according to the instant invention offer the advantage that, in the center region of the tread, the drainage ability of the tread profile toward the inside region, which is known to be of primary importance, is improved by the grooves at least nearly traversing the center region. Because not all of the transverse grooves have such a continuation from the shoulder block row into the center region, the creation of excessively narrow profile positives in the center region is avoided with the specified acute-angle design of the grooves. This measure is advantageous not only for tread wear but, e.g., also for the rolling noise produced. Specifically, in the center region, abrupt impacts in the inlet and undesired oscillations in the outlet are avoided. Moreover, due to the remaining residual impulses, only frequencies with a half-tone pitch in comparison with the impulses from the shoulder are generated in the tread center region, which results in a mixed frequency that is pleasant to the human ear.
Depending on the path of the grooves in the center region of the tread, alternative embodiments of the invention can be provided in which only every third or every fourth transverse groove continues from the shoulder block row of the inside region into the center region as a groove that at least nearly traverses it the center region.
With tread profiles designed according to the invention, it is therefore possible to orient the grooves in the center region at relatively acute angles to the circumferential direction of the tire. In this regard, an embodiment may be preferable in which such grooves form an angle of less than or equal to approximately 20xc2x0 to the equator line at their end regions lying by the outside region.
For the rigidity of the tread profile and, therefore, the wear pattern and driving behavior, it may be advantageous when the grooves of the center region end in a space that is a maximum of approximately 10% of the tread width, and preferably a maximum of approximately 5% of the tread width, before the circumferential groove of the outer region which delimits the center region.
Toward the circumferential groove delimiting the center region in the inside region, the angle to the circumferential direction formed by the grooves becomes larger. The angle can be selected such that it is, e.g., between approximately 30-65xc2x0, and preferably a maximum of approximately 50xc2x0. This design is advantageous for the water drainage ability of the profile.
In that regard, it is also advantageous when the remaining transverse grooves continue from the shoulder block row of the inside region in the center region or up into that region, at least in some cases, as blind grooves that are much shorter than the grooves. The blind grooves preferably end in the region of the equator line, which is also a measure to promote drainage ability.
According to an additional feature of the invention, to avoid a profile rigidity that is unfavorable for wear in the center region of the tread profile, the profile structures in the center region can be divided by additional narrow channels that have a slope in the opposite sense from the grooves and are formed to be less deep than the grooves.
The outside region is designed such that the circumferential groove arranged adjacent to the shoulder block row is constructed as a narrow groove that runs straight in the circumferential direction.
For a good response to steering forces and driving behavior, it can be also advantageous when at least one tread strip is disposed within the outside region and between the circumferential groove adjacent to the center region and the shoulder block row of the outside region.
In the inside region, a circumferential groove delimiting the center region and the shoulder block row of the inside region is preferably constructed as a groove running straight in the circumferential direction.
For tires with wide dimensions, it may be advantageous when an additional block row is located between the shoulder block row of the inside region and the center region. This arrangement allows the tread profile to be widened while retaining the desired profile characteristics.
Even wear of t he tread profile can be further promoted in that each transverse groove, after passing through a circumferential groove in a direction toward the center of the tire, continues such that a continuation of a lower edge of the transverse groove on the inside side of the circumferential groove merges from a profile structure located further outside into an upper edge of the transverse groove, the blind groove, or the groove of the adjacent profile structure that is located further inside.
The present invention is directed to a vehicular pneumatic tire having an asymmetric tread formed in relation to a circumference of a running surface. The vehicular pneumatic tire includes an outside region that includes an outside shoulder block row and an outside circumferential groove, an inside region that includes an inside shoulder block row and an inside circumferential groove, and a center region that is laterally delimited by the outside circumferential groove and the inside circumferential groove. A plurality of transverse grooves are arranged within the inside shoulder block row, and the plurality of transverse grooves further are arranged to extend into the center region. No more than one-half of the plurality of transverse grooves are arranged to at least nearly entirely traverse the center region and are oriented to form an angle to a circumferential equator line of no more than approximately 30xc2x0 over at least one-third of their longitudinal extensions.
According to a feature of the instant invention, the no more than half of the plurality of transverse grooves can include every other transverse groove in the inside shoulder block row. Alternatively, the no more than half of the plurality of transverse grooves can include every third transverse groove in the inside shoulder block row. Further still, the no more than half of the plurality of transverse grooves can include every fourth transverse groove in the inside shoulder block row.
In accordance with another feature of the instant invention, the center region can include approximately 25-35% a total width of the tread.
According to still another feature of the present invention, the no more than one-half of the plurality of transverse grooves are further arranged to form an angle to the equator line of no more than approximately 20xc2x0 to the equator line at their longitudinal ends located in a region of the outside region.
In accordance with a further feature of the present invention, the no more than one-half of the plurality of transverse grooves arranged to at least nearly entirely traverse the center region can be arranged to end at a position before the outside circumferential groove that is a distance of no more than approximately 10%, and preferably no more than approximately 5%, of an entire tread width from the outside circumferential groove. Further still, the no more than one-half of the plurality of transverse grooves arranged to at least nearly entirely traverse the center region can be arranged to extend through the center region and to open into the outside circumferential groove.
The no more than one-half of the plurality of transverse grooves may be oriented to form an angle to the circumferential equator line of between approximately 30-65xc2x0, and preferably no more than 50xc2x0, where these grooves open into the inside circumferential groove.
A remaining plurality of transverse grooves continue from the inside shoulder block row into the center region blind grooves which are much shorter than the plurality of transverse grooves arranged to at least nearly entirely traverse the center region. the blind grooves end in a region of the circumferential equator line, and the plurality of transverse grooves arranged to at least nearly entirely traverse the center region cross the circumferential equator line.
Further, the center region may include profile structures which are divided by additional narrow channels having a slope in an opposite sense from the transverse grooves arranged to at least nearly entirely traverse the center region. A depth of the narrow channels is less deep than a depth of the transverse grooves arranged to at least nearly entirely traverse the center region.
According to a still further feature of the present invention, the outside region can further include narrow circumferential groove positioned adjacent the outer shoulder block row arranged to run straight in the circumferential direction. The outside region may further include at least one tread strip positioned between the outside circumferential groove and the narrow circumferential groove.
Moreover, the inside circumferential groove, which is arranged to delimit the center region and the inside shoulder block row, may be a wide groove arranged to run straight in the circumferential direction. The inside region can further include an additional block row positioned between the inside shoulder block row and the center region. The plurality of transverse grooves, when extending through the inside circumferential groove, can be circumferentially offset on an opposite side of the inside circumferential groove. Further, each of the plurality of transverse grooves may be offset such that a lower edge of each transverse groove entering the inside circumferential groove continues as an upper edge of the transverse groove leaving the inside circumferential groove.
The inside region can further include an additional circumferential groove. The additional block row can delimited by the inside circumferential groove and the additional circumferential groove. The plurality of transverse grooves, when extending through the inside circumferential groove and through the additional circumferential groove, may be circumferentially offset on an opposite side of the inside circumferential groove and the additional circumferential groove, respectively. Further, each of the plurality of transverse grooves may be offset such that a lower edge of each transverse groove entering the inside circumferential groove continues as an upper edge of the transverse groove leaving the inside circumferential groove.
According to yet another feature of the invention the center region may include approximately 25-35% a total width of the tread. The no more than one-half of the plurality of transverse grooves may be further arranged to form an angle to the equator line of no more than approximately 20xc2x0 to the equator line at their longitudinal ends located in a region of said outside region. The no more than one-half of the plurality of transverse grooves can be arranged to at least nearly entirely traverse said center region are arranged to end at a position before the outside circumferential groove that is a distance of no more than approximately 10% of an entire tread width from the outside circumferential groove. The no more than one-half of the plurality of transverse grooves may be oriented to form an angle to the circumferential equator line of between approximately 30-65xc2x0 where these grooves open into said inside circumferential groove. Further, a remaining plurality of transverse grooves can continue from the inside shoulder block row into the center region blind grooves which are much shorter than the plurality of transverse grooves arranged to at least nearly entirely traverse the center region.
The present invention is directed to a vehicular pneumatic tire having an asymmetric tread formed in relation to a circumference of a running surface. The vehicular tire includes an outside region having an outside shoulder block row and an outside circumferential groove, an inside region having an inside shoulder block row and an inside circumferential groove, and a center region that is laterally delimited by the outside circumferential groove and the inside circumferential groove. A plurality of inside transverse grooves are open into the inside circumferential groove, and a plurality of center transverse grooves are arranged within the center region to extend from the inside circumferential groove at least nearly through the center region. The plurality of center transverse grooves are oriented to form an angle to a equator line of no more than approximately 30xc2x0 over at least one-third of their longitudinal extensions. A ratio of the plurality of inside transverse grooves to the plurality of center transverse grooves is at least 2:1.
In accordance with a feature of the invention, the ratio is 3:1. Alternatively, the ratio is 4:1.
According to another feature of the invention, a remaining number of the inside transverse grooves can extend through the inside circumferential groove and into the center region as blind grooves. The blind grooves do not extend to the equator line, and the center transverse grooves cross the equator line.
Further, the inside transverse grooves can be circumferentially offset from the center transverse grooves. The inside transverse grooves may be offset from the center transverse grooves in that a lower edge of the inside transverse grooves entering the inside circumferential groove continues as an upper edge of the center transverse grooves leaving the inside circumferential groove.
The present invention is directed to a process of making a vehicular pneumatic tire having an asymmetric tread formed in relation to a circumference of a running surface. The process includes forming an outside region to include an outside shoulder block row and an outside circumferential groove, forming an inside region to include an inside shoulder block row and an inside circumferential groove, and laterally delimiting a center region with the outside circumferential groove and the inside circumferential groove. The process further includes arranging a plurality of transverse grooves within the inside shoulder block row and to extend into the center region. No more than one half of the plurality of transverse grooves are arranged to at least nearly entirely traverse the center region and are oriented to form an angle to a circumferential equator line of no more than approximately 30xc2x0 over at least one-third of their longitudinal extensions.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.